SHANGHAI (Reuters) -China’s latest COVID-19 outbreak is developing rapidly, a health official said, as the authorities demanded high vigilance at ports of entry amid growing infections in a northeastern border city caused by the virus arriving from abroad. Some 377 domestically transmitted cases with confirmed symptoms were reported from Oct. 17-29, National Health Commission (NHC) data showed. China has tackled a series of outbreaks this year since it largely contained a national spread in early 2020. The numbers remain tiny compared with clusters outside the country. However, while the rest …